This invention relates to a ferromagnetic multiple shell core for electric coils.
When using wireless measurement transmission by means of an inductive close-range transmission system, particularly between a stationary machine part or vehicle part and a machine part or vehicle part that is movable with respect to it, the problems of targeting control of the magnetic flow, of reducing stray fields as well as improving the crosstalk attenuation between different signal levels are encountered.
With wireless measured-value transmitting systems, several signals must often be transmitted at the same time. For example, for the operation of a sensor on a rotating machine part or vehicle part, it is necessary to supply the sensor, by means of a (wirelessly transmitted) energy signal, with the energy required for the measurement and the generating of the measurement transmitting signal.
Conventional mass cores or ferrite cores are known, for example, from DE-AS No. 10 11 087. These devices known as shell cores are intended for the enlargement or for the alignment of coil sections. When these are divided into halves and each half is assigned to the stationary and to the movable machine part or vehicle part, they may be used for the bunching of the magnetic flux of an inductive close-range transmitter system.
However, when several signals must be transmitted at the same time via several pairs of coils, it is necessary to wind several coils onto one shell core.
Further, because of the strong inductive coupling on one magnetic circuit and because of the high winding capacitance between the individual coils, a very strong crosstalk of the signals of the individual signal levels is generated that must be eliminated by means of expensive filters before further processing.
DE-AS No. 12 77 460 shows a ferromagnetic multiple shell core for electric coils that mitigates the problem of crosstalk attenuation.
However, due to its arrangement, the multiple shell core is completely unsuitable for the intended purpose because the individual coils are located far away from one another in the core material and are arranged partially vertically to one another.
It is therefore an object of this invention to provide a ferromagnetic multiple shell core for electric coils that has a high crosstalk attenuation between the windings as well as a winding capacitance that is as small as possible.
Another object of the invention is to provide a ferromagnetic shell core for electric coils which is especially suitable for close-range transmission.
A further object of the invention is to provide a ferromagnetic shell core for electric coils which can be produced in a simple and cost-effective way.
These objects are achieved by providing a ferromagnetic shell core for electric coils with a plurality of concentrically arranged side core walls, a bottom core wall and a central core at a center-point of the side core walls. A plurality of concentrically arranged recesses are thus formed between the central core and a side core wall and between each of the side core walls. These recesses house windings of coils.
Advantages of the invention are that a ferromagnetic multiple shell core for electric coils is provided that, because of several separate winding spaces, ensures a good crosstalk attenuation with a low winding capacitance between the individual coils. Because of the good decoupling of the magnetic circuits and the low winding capacitance, high crosstalk attentuations between the different signal circuits can be achieved together with an advantageous mechanical structure. Further, the invention has a compact construction, while the coils are advantageously arranged with respect to space, and can be produced in a simple and cost-effective way.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.